Systematics is the branch of evolutionary biology that studies the diversity and relationships of organisms, and analyses their evolution in space and time. The research group studies a wide range of aquatic invertebrates, focusing mostly on Copepoda (copepods), Cladocera (water fleas) and Ostracoda (seed shrimp) among the microcrustaceans, Odonata (dragonflies and damselflies) among the aquatic insects, and Rotifera (rotifers). One of the principal research themes of the group focuses on molecular phylogenetic, evolutionary and biogeographic relationships between organisms. The molecular phylogenetics is combined with morphological and biogeographical research, in order to provide a better insight in the diversity, the relationships, and the evolutionary history of each group. It is essential to have information on family and species relationships and to know which organisms are closely related to each other and thus share a common ancestor. The biogeography and phylogeography of present and past species are studied, and the distributional patterns of organisms over space and time are analysed to better understand species distribution over the globe and changes during their evolutionary history